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Biomedical subjects

A Bossuyt

Publications and source records attributed to A Bossuyt.

At least 73 records · Page 4Linked to original sources
PubMed1991

Technetium-99m-MRP20, a potential brain perfusion agent: in vivo biodistribution and SPECT studies in normal male volunteers.

The lipophilic neutral complex [99mTc][TcO(MRP20)] [MRP20 is (N-(2(1H pyrolylmethyl]N'-(4-pentene-3-one-2)ethane-1,2-diamine)] is known to cross the blood-brain barrier in non-primate animals. We report here its in vivo biodistribution, radiation dosimetry, and single-photon emission computed tomography (SPECT) characteristics in man. Following i.v. administration of 15-25 mCi of the tracer, the maximum uptake of activity in the brain peaked at 1 min p.i. Fifteen minutes p.i., the percentage retained in the brain was 5.2 +/- 1.6, which remained fairly constant over 24 hr. Blood clearance was relatively slow with an apparent affinity of the compound for the cellular fraction of the blood, however, soft-tissue and facial activity cleared at a rate four times faster than that of the brain. SPECT images obtained at 15 min, 1 hr, 3 hr, 7 hr, and 24 hr p.i. showed no redistribution of the tracer within the brain. The dosimetry is favorable for administration of 25-30 mCi of MRP20. Our results indicate that this compound is rapidly extracted and retained by the brain and may be used for SPECT imaging of regional blood flow.

Adult↗
PubMed1991

Technetium-99m-MRP20, a potential brain perfusion agent: in vivo biodistribution and SPECT studies in non-primate animals.

MRP20 (N-(2(1H pyrolylmethyl]N'-(4-pentene-3-one-2] ethane-1,2-diamine) complexes with technetium-99m, yielding a neutral, lipophilic species. This compound has been characterized as [TcO(MRP20)]. Biologic investigation of [99mTc][TcO(MRP20)] in female rats showed 2.35% ID in the brain 30 min p.i. with no significant wash-out over 3 hr. A single-photon emission computed tomography (SPECT) study in a dog demonstrated rapid tracer uptake in the brain, reaching a maximum within 1 min, with 2.24% i.d. 15 min p.i., decreasing to 1.7% after 4 hr. The complex undergoes hydrolysis in vitro forming a cationic species. This is possibly the trapping mechanism in the brain in vivo. The main excretory route of [99mTc][TcO(MRP20)] is via the hepatobiliary tract. There is evidence of some "in vivo" cell labeling and soft-tissue uptake.

Animals↗
PubMed1989

Acute effects of oxygen, nifedipine, and diltiazem in patients with cystic fibrosis and mild pulmonary hypertension.

The acute effects of oxygen, nifedipine, and diltiazem were studied in eight patients with cystic fibrosis and mild pulmonary hypertension, to assess the possibility of relieving the latter before the occurrence of irreversible vascular changes. Oxygen decreased pulmonary pressure (-23%) and resistance (-21%), while increasing systemic resistance (+23%). Nifedipine increased cardiac index (+30%), at the expense of augmented right ventricular work (+42%), resulting in a decreased calculated pulmonary resistance (-23%); pulmonary artery pressure remained unchanged, however. Nifedipine decreased arterial Po2 (-10%), suggesting ventilation-perfusion mismatch. Four of the eight patients responded to diltiazem. Their pulmonary pressure (-35%) and resistance (-43%) decreased, while systemic vascular tone remained unchanged. Oxygen in three patients, and diltiazem in two, returned pulmonary pressures and resistances to normal values. Early reversal of pulmonary hypertension is possible, and intervention is desirable before the establishment of chronic hypoxia, cor pulmonale, or right ventricular failure. Our data does not support the use of nifedipine in pulmonary hypertension, but shows that oxygen, and in some cases diltiazem, act as effective and selective pulmonary vasodilators.

Adolescent↗
PubMed1989

Pre- and peroperative diagnosis of metastatic pheochromocytoma in multiple endocrine neoplasia type 2a.

A 37-year-old woman with a multiple endocrine neoplasia type 2a underwent bilateral adrenalectomy and total thyroidectomy with parathyroidectomy in 1977. The left-sided pheochromocytoma was considered to be malignant. Seven yr after the initial operation, an enhanced urinary excretion-ratio of N-methyladrenaline/adrenalin suggested the possible presence of either persistent or metastatic pheochromocytoma Iodine-123-labeled metaiodobenzylguanidine scintigraphy (I-123 MIBG) showed a hot spot in the right lung. However, repeated chest-X-rays and computed tomographic scanning of the thorax remained negative. Anatomical localization of the lesion was finally obtained with magnetic resonance imaging. The surgical removal of the small pheochromocytoma was guided by the gamma-ray emission of I-123 MIBG administered iv before the operation. This case report illustrates the usefulness of new analytical methods and of new imaging techniques in the diagnosis and management of metastatic pheochromocytoma.

Adult↗
PubMed1989

Radionuclide assessment of right ventricular regional wall motion abnormalities in anterior left ventricular infarction.

Because of its potential use in the detection of right ventricular myocardial infarction, we performed radionuclide ventriculography in 80 consecutive cases of electrocardiographically anterior acute MI. Regional wall motion of both ventricles was studied on amplitude-phase images. Forty-five patients (56%) showed normal right ventricular function and 35 (44%) regional right ventricular dyskinesia: 19 in the septal, 14 in the apical and 2 in the free wall region. Right ventricular septal, respectively apical asynergy were virtually always associated with asynergy in the homologous parts of the left ventricle. This could be a consequence of the proximity of these regions, or alternatively be due to a common vascular supply. Thus it remains uncertain if asynergy in these regions signifies necrosis of part of the right ventricular wall. Free wall asynergy was considered as evidence of right ventricular wall necrosis. Thus, in our study group the prevalence of right ventricular myocardial infarction in anterior left ventricular myocardial infarction was at least 2.5%.

Adult↗
PubMed1989

Effect of PEEP on regional ventilation and perfusion in the mechanically ventilated preterm lamb.

Improvement of gas exchange through closer matching of regional ventilation (V) and lung perfusion (Q) with the application of positive end-expiratory pressure (PEEP) was evaluated in vivo in six mechanically ventilated preterm lambs (107-126 days/145 days gestation). Changes in V and Q were determined from in vivo scintigraphic measurements in four lung regions with inhaled radioactive 81mKr, and infused 81mKr/dextrose and/or [99mTc]MAA as PEEP was applied at 2, 4, and 6 cm H2O in each animal. Dynamic compliance varied between 0.02 and 0.40 ml/cm H2O, which was consistent with surfactant deficiency. As PEEP was increased, the regional distribution of Q shifted from the rostral to the caudal lung regions (p less than 0.02 to less than 0.05), while that of V remained unchanged. Regional V/Q matching improved together with a trend towards improvement of arterial blood gases as PEEP was increased from 2 to 4 cm H2O. Pulmonary scintigraphy offers a noninvasive methodology for the quantitative assessment of regional V and Q matching in preterm lambs and may be clinically applicable to ventilated neonates.

Animals↗
PubMed1989

Hemodynamics of patients with renal failure treated with recombinant human erythropoietin.

Hemodynamics were evaluated in 8 patients with uncomplicated renal failure on regular dialysis before and after partial correction of anemia by treatment with recombinant human erythropoietin (r-huEPO). Under r-huEPO treatment, mean (+/- SD) hemoglobin increased from 7.51 (0.60) to 10.27 (0.92) g/dl. Mean blood pressure, body weight, total blood volume and extracellular fluid compartment remained unchanged. Cardiac output as measured with a radionuclide method increased significantly from 4622 (1069) to 5393 (1285) units (p less than 0.02) and peripheral resistance decreased from 22 (4) to 19 (3) units (p less than 0.02). 6-keto-1-alpha-prostaglandin decreased from 96.9 (54.4) to 61.6 (18.0) pg/ml (p less than 0.05) but plasma renin activity, noradrenalin and atrial natriuretic peptide remained unchanged comparing pre- and post-treatment levels. This observation suggests that an increase of red blood cell mass can improve heart function in patients undergoing regular dialysis treatment.

Adult↗
PubMed1988

Iodine-123 MIBG imaging in a generalized pancreatic polypeptide-gastrin-serotonin secreting tumor.

The usefulness of radio-metaiodobenzylguanidine (MIBG), a specific radiopharmaceutical agent for scintigraphic imaging and treatment of phaeochromocytoma and neuroblastoma, has been extended to the location of carcinoid tumors. Scintigraphic evaluation with I-123 MIBG in a patient with a histologically proven endocrine tumor (apudoma) of unknown origin with liver and bone metastases is reported. Elevated plasma hormone levels of gastrin, pancreatic polypeptide, and serotonin were found. Tumoral content of these hormones was immunocytochemically confirmed on liver biopsy. I-123 MIBG uptake could be seen in those areas of the liver with deficient lesions in the Tc-99m colloid image with a maximal uptake in a large mass at the level of the left liver lobe. No abnormal uptake could be observed at any other level, which was in contrast with autopsy findings of generalized metastatic disease.

3-Iodobenzylguanidine↗
PubMed1986

Fast, low-temperature preparation of carrier-free 17-123I-heptadecanoic acid applied for liver and heart scintigraphy.

A high-yield method for labelling 17-I-heptadecanoic acid with 123I is described, and a clinical evaluation of the radiopharmaceutical is given. The labelling procedure is based on the use of a conventional ultrasonic bath. It was found that the addition of thiosulphate to the reaction medium avoids the formation of labelled side products and increases the yield considerably. The carrier-free 17-123I-heptadecanoic acid (2 mCi) in 6% human serum albumin was injected IV for heart and liver studies on selected patients with cirrhosis (alcoholic, post-necrotic) and diabetes.

Diabetes Mellitus, Type 1↗
PubMed1985

Radionuclide evaluation of left ventricular synergic pumping efficiency during acute myocardial infarction.

The clinical value of an index of left ventricular synergic pumping efficiency (EFF) was evaluated in 50 patients with uncomplicated myocardial infarction in which radionuclide ventriculography was performed within 72 h of the onset of the infarction and between 7 and 13 days post infarction. EFF was defined as the ratio of global left ventricular stroke volume to the magnitude of all intraventricular blood pool variations measured on a pixel by pixel basis. EFF correlated better with a subjectively evaluated wall motion index (r = 0.84) than did the ejection fraction (EF) measurements (r = 0.69). In all patients, but most significantly in patients with inferoposterior infarctions, EFF measurements in the acute phase were a better predictor of the predischarge ventricular performance than the EF measurements. The left ventricular EFF is a reliable parameter to quantitate the effect of regional wall motion disturbances on global ventricular function in a standardized manner.

Adult↗
PubMed1985

Clinical and scintigraphic evaluation of corticosteroid treatment in a case of progressive diaphyseal dysplasia.

A case of progressive diaphyseal dysplasia (Engelmann's disease) is described in a 23-year old woman. The disease is characterized by limb pain, muscular wasting, a waddling gait and easy fatiguability. It is diagnosed radiologically by cortical thickening, a narrowed medullary cavity, and increased diameter of the diaphyses of the long bones. The extension of the bone lesions was evaluated by scintigraphy using 99mTc methylene diphosphonate (MDP) and 99mTc colloids. Corticosteroid treatment resulted in clinical improvement and reduction of the diaphyseal uptake of MDP and colloids.

Adrenal Cortex Hormones↗
PubMed1983

Effect of neck position during radionuclide superior cavography. Its value in the diagnosis of superior vena cava obstruction due to retrosternal goiter.

In five patients with substernal goiter, three of whom presented with superior vena cava (SVC) syndrome, and in five normal subjects, radionuclide superior cavography (RNSC) was performed with extension and flexion of the neck during tracer administration (simultaneous bilateral injection of Tc-99m pertechnetate). When the tracer was injected during neck extension, venous flow pattern was abnormal in four of five patients, and transit time (TT) prolonged in three of five patients. In this posture, mean TT +/- 1 standard deviation (SD) was 6.3 +/- 2.6 s (range 3.5 to 9 s) for the five patients and 3.5 +/- 0.7 s (range 2.5 to 4.5 s) for a group of five control subjects. When the tracer was injected during neck flexion, all five patients showed abnormal flow patterns and prolonged TT (mean +/- 1 SD 10.1 +/- 4.1 s; range 4.4 to 16 s), in contrast to the control group where a slight decrease in TT was found (mean +/- 1 SD 3 +/- 0.6 s; range 2 to 3.5 s). In the presence of a substernal goiter, or any mobile mass at the thoracic inlet, impairment of venous flow through the SVC system appears to be a common occurrence, readily detectable by RNSC. RNSC should be performed with neck flexion during tracer injection, since in this posture its ability to detect compromised venous flow through the SVC system is enhanced, even in patients without a clinically apparent SVC syndrome.

Adult↗